1. Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands
2. Headache Unit, IRCCS Neuromed, Pozzilli, Italy
3. Department of Neurology, Mayo Clinic, Scottsdale, Arizona, USA
4. Department of Neurology, Istanbul University, Istanbul Faculty of Medicine, Istanbul, Turkey
5. Department of Neurology, Albert Einstein College of Medicine, Bronx NY, USA
6. Headache Science & Neurorehabilitation Center, IRCCS Mondino Foundation, Pavia, Italy
7. Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
8. Department of Neurology, Danish Headache Centre, University of Copenhagen, Rigshospitalet Glostrup, Glostrup, Denmark
9. Headache Unit, Neurology Department, Vall d'Hebron University Hospital, Barcelona, Spain
10. Headache and Neurological Pain Research Group, Vall d'Hebron Research Institute, Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain